You’ll see them dotted all around the Utrecht countryside: ancient forts and concrete bunkers, casements and hideouts. Together they form a defence line that was designed to protect the Netherlands from hostile attack. The surrounding landscape is great for a bike ride. The Defence Line of Amsterdam (Stelling van Amsterdam) and the New Dutch Water Line (Nieuwe Hollandse Waterlinie) are jointly known as the Dutch Water Lines. Together, they form two hundred kilometres of defence lines that run from Edam in Noord-Holland to the Biesbosch in Zuid-Holland. The advent of fighter planes made the Line redundant as a defence strategy and it fell into decline in the 1950s. Open green spaces with fields and meadows emerged around the Lines, because building was not permitted on areas that had been flooded. These days, most of the edifices are still intact and have been given a new lease of life. A bike ride past the highlights of the Dutch Water Lines will take you through different landscapes and past forts, castles, windmills, rivers, dykes and bunkers. For more information, go to hollandsewaterliniesfietstour.nl